The invention relates to the field of modulators, and in particular to an electrically driven Mach-Zehnder waveguide modulator based on high-index contrast silicon waveguide technology and electronic carrier injection.
The development of future electronic-photonic integrated circuits based on silicon technology critically depends on the availability of CMOS-compatible high-speed modulators that enable the interaction of electronic and optical signals. Si-based phase modulators using the plasma dispersion effect in a p+in+-structure have been proposed for silicon-based opto-electronic phase and amplitude modulators. Switching speeds up to 10 MHz have been demonstrated and up to 1 GHz are predicted. The speed of the response in these devices is limited by carrier recombination. Very recently a modulator based on a MOS structure has been proposed operating at 1 GHz speed. However, this device needs an applied voltage of 10V for achieving a π phase shift within 1 cm length and showed 6.7 dB loss due to the doped polysilicon rib-waveguide. Much lower drive voltage in the order of 1-5V is needed, when feed by CMOS circuitry. The same is true for top contacted rib-waveguides of previously proposed pin-structures.